(NaturalNews) A majority of the estimated four in 10 hospital websites in the United States that publicize the use of robotic surgery, tout the superiority of robotic surgery over conventional surgery, despite a lack of scientific evidence to support that claim, a new Johns Hopkins study finds.

The promotional materials on the hospital websites overestimate the benefits of surgical robots, largely ignore the risks and are strongly influenced by the product's manufacturer, according to the report in Journal for Healthcare Quality.

"The public regards a hospital's official website as an authoritative source of medical information in the voice of a physician," said Marty Makary, associate professor of surgery at the Johns Hopkins University School of Medicine and lead researcher of the study. "But in this case, hospitals have outsourced patient education content to the device manufacturer, allowing industry to make claims that are unsubstantiated by the literature. It's dishonest and it's misleading."

More hospitals are buying the expensive new equipment and many use aggressive advertising to lure patients who want to be treated with what they think is the latest and greatest in medical technology, Makary said. In the last four years, he added, the use of robotics to perform minimally invasive surgeries and other types of common procedures has grown 400 percent.

Proponents say robot-assisted operations use smaller incisions, are more precise and result in less pain and shorter hospital stays. But there are no randomized, controlled studies showing patient benefit in robotic surgery, Makary said. In fact, robotic surgeries take more time, keep patients under anesthesia longer and are more costly.

Manufacturer-provided materials were used on 73 percent of websites, while 33 percent directly linked to a manufacturer website.

"This is a really scary trend," Makary says. "We're allowing industry to speak on behalf of hospitals and make unsubstantiated claims."

When describing robotic surgery, the researchers found that 89 percent made a statement of clinical superiority over more conventional surgeries, the most common being less pain, shorter recovery, less scarring and less blood loss. Thirty-two percent made a statement of improved cancer outcome. None mentioned any risks.

Makary says the use of manufacturer-provided images and text also raises serious conflict- of-interest questions. He says hospitals should police themselves in order not to misinform patients. Johns Hopkins Medicine, for example, forbids the use of industry-provided content on its websites.

"Hospitals need to be more conscientious of their role as trusted medical advisers and ensure that information provided on their websites represents the best available evidence," he says. "Otherwise, it's a violation of the public trust."